1. Field of the Invention
The present invention relates to conference systems and terminal apparatuses for the same. More particularly, the present invention relates to a conference system in which communication data including audio information generated at a conference is exchanged between terminal apparatuses as well as access restrictions to system resources are performed on the basis of preset access control information and a terminal apparatus for the same.
2. Description of the Related Art
As represented by videoconference systems, conference systems that are used to implement electronic conferences by sending and receiving audio/video information through a plurality of conference terminal apparatuses placed at remote locations have been constructed.
In such systems, the following procedure has to be performed before starting a conference. First, a group of conference participants is defined, and conference participation rights are granted to them. The information on the conference participation rights is then set in a management server that controls the conference system. Accordingly, an administrator of the conference system invokes a control application in the management server to set the access control information beforehand. The access control information includes general information used for the access restrictions to the conference system resources, such as a group definition and an access right to shared files. When implementing the conference, the management server of the conference system performs access privilege management processing on the basis of an access control list that has been set in the above-described manner. More specifically, the management server determines whether or not a user of the conference system is authorized to participate in the conference, and to access the shared files on the basis of the access control list.
Access privilege management techniques (see, for example, Japanese Unexamined Patent Application Publication No. 2004-15507, paragraphs [0186] to [0190] and FIG. 26) have been proposed. In this example technique, group attribute certificates including group identification information are issued to each group of specific users with electronic signatures. Also, each group is associated with service providing conditions. When a user requests to access a service, the group attribute certificates are obtained to confirm the user's access privileges. Only the authorized users or groups can access the requested service.